In the vast majority of home in the United States there is no alternating current (AC) electrical outlet available for providing 220 Volt power, not even in the kitchen. The electrical outlets are usually nominally rated at 110 to 120 Volts AC at 15 Amperes of current. This rating meant that the maximum amount of electric power which is usually available from any such conventional outlet is approximately 1,650 Watts, assuming that there is no other electrical load being imposed on the circuit which is energizing the specific outlet.
The electrical power for energizing a resistance type of appliance, for example such as a heater, a wok, an oven, or an electric frying pan, is calculated as the product of the amperage times the voltage, which may be expressed as: EQU P=I.times.E
where "P" is the power in Watts, "I" is the effective AC current, and 37 E" is the effective AC voltage. Thus, the maximum amount of power available at nominal 15 Amps. and nominal 110 Volts is about 1,650 Watts. If an attempt is made to draw more power than this maximum from any given circuit in the home, the limit of 15 Amps. will be exceeded, and the protective circuit breaker or fuse for that particular circuit will be tripped or melted in order to prevent over-heating of the wiring or connections in that circuit.
It would be desirable to have a higher level of electric power available in the home kitchen for certain types of very modern electrical appliances, such as woks, frying pans, and convection ovens, etc. However, at the present time such types of very modern higher power appliances are not practicable for the typical American home, because most consumers do not wish to undertake the significant expense and disruption of employing an electrician to install a 220 Volt power line extending from the electrical panel box to a special outlet in the kitchen.
It is to be noted that the kitchens in many, many homes in the U.S.A. are already equipped with electric ranges which are energized by a 220 Volt electrical circuit at approximately 50 Amperes and sometimes more. Thus, the electrical power for consumption in an electric range is approximately four to six, or more, times greater than the power which is available from a conventional 110 Volt electrical outlet.
As used herein the term "110 Volt" is used in an inclusive nominal sense to include all of the various levels of AC voltages which are actually available in conventional wall outlets in homes in various regions of the U.S.A., namely from about 105 Volts, or sometimes less, up to about 125 Volts, or sometimes more.
It is to be understood that the voltage actually available at any given time will depend upon many factors, including the over-all loads on the electric utilities. Moreover, AC voltages as nominally expressed are measured in accordance with a root mean square (R.M.S.) measurement.
Similarly, as used herein the term "220 Volt" is used in an inclusive nominal sense to include all of the various levels of AC voltages which are actually available for energizing kitchen ranges in homes in various regions of the U.S.A., namely from about 210 Volts, or sometimes less, up to about 250 Volts, or sometimes more.
As used herein the term "electric range" is used generically to include all of the types of electric kitchen cooking equipment which have removable electrical heater elements in top surfaces which are usually at approximately the level of counter tops, such equipment sometimes being called "electric stoves" or "cook tops", and even including electric ovens which often have removable electrical heater elements in top surfaces sometimes located above an oven chamber and sometimes located below and in front of an oven chamber.